2012/11/23
The cost of LED lighting has been a major obstacle to hinder people to buy energy-efficient LED bulb. Now, the world's largest manufacturer of an LED OSRAM Opto Semiconductors (Osram Opto Semiconductors) said that it has perfected the technology, can significantly reduce the production costs of LED.

The white LED Preparation usually coated with a yellow phosphor to blue GaN LED. The the manufacturers usually cultivate a thin layer of gallium nitride is expensive sapphire substrates. On the contrary, Osram preparation of such devices on silicon substrates. The cost of the silicon substrate is more than one-third of the sapphire, and even cheaper, because the sheet can be made greater.

The company said that its silicon-based white LED per watt of power can produce 127 lumens power efficiency of 58%, comparable sapphire nurture the most state-of-the-art commercial LED. Peter Stas (Peter Stauss), is the project manager of Osram, he said, researchers are testing and optimization of such devices, expected to start selling them in the next two to three years.

OSRAM joint several other companies strive to the cheaper silicon gallium nitride light-emitting diode market. China the LatticePower Corporation (Lattice Power) claims, has begun commercial production, using the same technology. Last month, California (California) new record company Puri (Bridgelux) announced cooperation with Toshiba, the preparation of silicon-based light-emitting diode. At the same time, Britain's Plessey Semiconductors (Plessey Semiconductors) program at the end of the production of silicon GaN light-emitting diode, using technology from the University of Cambridge (Cambridge University) run enterprises, Keim Gahan (CamGaN). Philips and Samsung are also said to be committed to silicon technology.

Osram said its new LED will be much cheaper, but Puri and Plessey Company are sound, this silicon technology can reduce the cost of LED production more than 75%. Puri company also predicted that its process can reduce the same 75-watt LED bulbs cost, now sell for $ 40, can be reduced to less than $ 5.

Compared with the sapphire, the preparation of large diameter silicon wafer is easier and cheaper, which can reduce costs. Another attractive grounds, steering silicon can take advantage of existing machines, these machines originally used to make silicon computer chips. Puri company has demonstrated some of the equipment, which is cultivated in 20 cm wide silicon.

The challenge of nurturing GaN on silicon, these two materials expand and speed of contraction. The light emitting diode is prepared at a high temperature, the light-emitting gallium nitride layer would crack when the material is cooled, this is because of the tension with the underlying silicon. To solve this problem, Osram and other companies cultivate additional material film, such as aluminum gallium nitride GaN around the tension generated in the cooling process, which can be balanced.

While many LED manufacturers have chosen to silicon, but California startups sweep pull (Soraa), but in the use of gallium nitride substrate. This also reduce the mismatch between the two layers of the crystal structure of sweep pull CTO Michael? Carat Metz (Michael Krames) say, 1,000 times less material defects, which is cultivated in contrast silicon material Introduction. The LED produced is more expensive than silicon substrates, however, they also brightening 10 times, which helps compensate for the additional cost. "Really LED performance drive the total cost of the light bulb," carat Metz said. "Furthermore, this substrate is a small part of the overall production costs."

Now, although Costa said, the cost advantage of the silicon substrate is more conducive to manufacturers than LEDs. The GaN substrate may be a choice, as long as they are much cheaper, but today there is no real opportunity to use them, "he said.